I have a Powervamp T6, that was recommended by Duncan Andrews. It works extremely well, I have used it to start several different vehicles already, but haven't had to use it on the race car yet! Duncan has even started his motorhome with it from absolutely flat. £74.75 including charging leads, usb adaptors and standard leads with croc clips. A spare set of leads was £4.75 to adapt to an Anderson connector. Great service from them, and they are reasonably local in Weston-super-Mare.
JW

I copied Dave and Nicola's starter battery. It was supplied via Mistral I think. It's an Enigma Batteries DS12 600 Amp Jump Battery which comes with an Anderson fitted. There is a charger lead, and a button to press to illuminate a charge level (red, yellow, green) indicator and that is it. Comes from Essex and works. Other makes available and lower prices too.